Character Analysis
Everyone has that one wacky uncle, right? But "Uncle" Victor takes the crazy uncle schtick to a whole new level. A family friend, not a blood relation, Sym's "Uncle" Victor is a straight-up psychopathic murderer. As readers, we realize this long before Sym does. Blinded by her love for him—"Uncle Victor has always been like a father to me" (14.23) she tells us—Sym is unable to spot his treachery until it's far too late. Gulp.
After Sym's father died, Uncle Victor stepped up to help Sym and her mom. Or at least that's what they thought he was doing. Behind the scenes, Victor had actually cashed in Sym's dad's life insurance policy and spent untold amounts of money arranging the Antarctic expedition that comprises the bulk of the book. Sym and her mom are totally not hip to this, though. So for the first part of the book, Sym sees Victor as a genius and a borderline superhero:
He knows at what temperature glass turns to liquid, and where Communism went wrong and how the Clifton Suspension Bridge was built and just what the Government ought to be doing. (1.4)
Sym gushes about his intelligence here, and as she tells us many times, he has an IQ of 184. So what's not to like?
Weird Science
In the beginning of the book, Sym spends a lot of time describing Victor's weird habits. He sleeps sitting up and thinks that mobile phones "interfere with signals in the brain" (3.20); he mows the grass in a particular pattern; he stores orange rinds in a tin under his bed. At first, we just see odd habits that we can almost write off as eccentricity. Gradually, though, it becomes clear that Victor's mental health is in tatters—he all but wears a tinfoil hat.
As the story progresses, his insanity becomes more intense and more sinister. In Antarctica, Victor tells Sym about Symmes's Hole, which he has been secretly obsessed with finding his whole life. Symmes's Hole was once a real theory, by the way—until it was debunked hundreds of years ago (source). No matter to Victor, though; he's intent on finding it and will destroy anything (or anyone) that gets in his way.
Dr. Horrible
As Victor and Sym search for Symmes's Hole, Victor's sinister aspect is brought into full focus as he makes a series of confessions that totally rock her world: He blew up a plane; he poisoned their fellow travelers; he murdered her father; he caused her deafness. (As perhaps the most British murderer in all of literature, Victor accomplished many of these things using poison teabags.) He is, of course, also the author of Sym's current predicament, as they travel over thin ice to fulfill his obsession.
Uncle Victor is self-absorbed to the point of seeming incapable of listening to anyone else. He's forever asking people to repeat themselves. Driving with him across the Antarctic wilderness, Sym says that "I could hear him but he could not hear me. That had a familiar feel, at least" (11.18). Ultimately this inability to listen to reason causes Victor to self-destruct; deluded into thinking he's finally found Symmes's Hole, he jumps into the abyss, which must mean certain death.
On some level, Sym is angry that Victor's destroyed her life, but she also knows he didn't so on purpose. Titus asks her, "Do you think that he meant to? Do you think it was done with malice?" (21.7) Ultimately, the answer is no, Sym doesn't think so: "It would be a precious foolish thing, to go on hating Uncle Victor for the rest of my life" (21.28), she realizes. And the fact that he deceived her doesn't negate the fact that she loved him.
Victor Briggs' Timeline